Method and apparatus for quenching



Feb. 6, 1968 A. TEPLITZ 3,367,804

METHOD AND APPARATUS FOR QUENCHING Filed May 7, 1965 2 Sheets-Sheet 1qll Attorney A. TEPLITZ 3,367,804

METHOD AND APPARATUS FOR QUENCHING 2 Sheets-Sheet 2 Feb. 6, 1968 FiledMay 7, 1965 Alli PIE: 2 ll? AIR AIR

INVENTOR ALFRED TEPL/TZ Uit States 3,367,804 METHOD AND APPARATUS FORQUENCHKNG Alfred 'Ieplitz, Pittsburgh, Pa, assignor to United StatesEitcei (Iorporation, a corporation of Delaware Filed May 7, 1965, Ser.No. 453fi25 8 Claims. (Cl. 148-443) ABSTRACT OF THE DISCLGSURE A methodand apparatus for quenching metal which is adaptable for use in acontinuous process. The apparatus comprises two plate members spacedfrom each other having an aligned passageway therewithin for the passageof work through the plates. The plates are disposed substantiallyperpendicular to the line of travel of the work and gas is propelledagainst the surface of the first plate member surrounding thepassageway, and liquid coolant is propelled against the surface of thesecond plate member surrounding the passageway. As a result, a.substantially planar mass of gas and a substantially planar mass ofliquid coolant are provided across the passageways of the first andsecond plate members.

This invention relates to quenching, is. rapid cooling or metal afterapplication of some thermal treatment. More particularly, the inventionrelates to method and apparatus for quenching which is adaptable incontinuous processing systems.

To develop and improve physical and metallurgical properties, variousthermal or heat treatments have been devised. In many heat treatments,it is important to rapid- -1y lower the temperature of the metalworkpiece after heating to elevated temperature to produce desiredmetallurgical structure and corresponding physical properties. Manyquenching systems have been proposed and used to accomplish rapidtemperature reduction from elevated temperature. Among these systems arethe relatively simple technique of immersing the metal workpiece in acoolant and more complex methods such as those involving the use ofsprays and mist.

In many metallurgical practices, it is desirable to initiate quenchingof a metal workpiece abruptly and with minimum premature cooling. Thus,the metal should be quenched as soon as possible after leaving the heattreating furnace. To this end, continuous heat treating systems havebeen designed with quenching systems adjacent the heat treating furnaceswith the aim of cooling the metal workpiece as quickly as possible as itemerges from the furnace. In continuous systems, it is necessary thateach successive increment of workpiece, as it moves through the quench,be contacted with coolant about its entire periphery at the same instantto insure straightness and uniform properties of the quenched product.Among the more popular quenching procedures have been those which employsprays from nozzles strategically located to accomplish the maximumcooling of the metal workpiece. Such spraying techniques, however,sutfer from the disadvantage that a good deal of splashing occurs whichmay cause premature cooling of the portion of the workpiece not yetwithin the quenching zone and back up of coolant into the furnace. Tominimize premature cooling and back up of coolant, a spray of gas, e.g.air, directed at a workpiece behind the coolant, has been used in anattempt to control coolant flow. Typically, quenching systems employ aplurality of nozzles aimed in a predetermined fashion to provide optimumcooling of a workpiece under static conditions. This approach furthersuffers from the obvious drawback that disruption of the idealconditions requires readjustment of the sprays for optimum quenching.Variations from the static conditions upon which designs are based occurfrequently in continuous systems because the metal may vary slightly insize and shape and its path of travel can also change somewhat.

The present invention avoids the aforementioned problems and provides amethod and apparatus for quenching metal which is adaptable for use incontinuous processing systems without the necessity of constantreadjustment. The quenching arrangement of the invention furtherprovides a sharp quench line without disadvantageous premature coolingof the metal workpiece and without undesirable back up of coolant intothe furnace. Because there is no danger of coolant back up into thefurnace, the apparatus can be positioned immediately adjacent the exitof the heat treating furnace for optimum metallurgical perforamnce.

The quenching system of the invention can be regarded as including twoquenching zones, although for light sections only the first of these maybe sufiicient to accomplish the desired rapid temperature reduction. Inthe first quenching zone are positioned two plate members spaced fromeach other and having aligned passageways for passage through them of ametal workpiece emerging from the heat treating furnace. The platemembers are positioned substantially perpendicular or normal to the lineof travel of the metal workpiece. Against the first of the plate memberslocated nearest the furnace is projected gas, e.g. air, around thepassageway in the plate. In a similar manner, a liquid coolant isprojected on the surface of the second plate also around the passageway.In this way, the substantially planar mass or curtain of gas and liquidcoolant is projected across the passageway of each of the plate membersthrough which metal from the heat treating furnace is passed. Thevelocity and volume of the gas projected against the first plate iscontrolled so that it is sufficient to prevent liquid coolant whichwould otherwise flow or splash backward after impinging on the metalworkpiece from doing so. As a consequence, a substantially fine quenchline results around the periphery of the traveling metal workpiecewhich, if an elongated section, is progressively cooled in increments bypassage through a curtain of liquid coolant. A particular advantage ofnormal to-the-work coolant impingement provided by the coolant plate isthat departures from the nominal pass line and of nominal workpiecedimensions will not disturb the simultaneity of quench around theperiphery of the workpiece (as would be the case with conventionalangled-spray quench arangements). Another important advantage of thissystem is that individual positioning and adjustment of a large numberof nozzles is avoided. Thus, it is apparent that my invention has theadvantage of requiring no fine adjustments of nozzles for quenching andcan tolerate considerable deviation in shape and path of travel of themetal workpiece.

As desired and according to the preferred embodiment of the invention, asecond quenching zone can be positioned immediately adjacent the firstquench zone, to accomplish further reduction in temperature of theinterior of the metal workpiece. This latter arrangement is particularlyadvantageous when treating relatively thick sections of metal such assteel in which the first quenching zone can be effectively employed toaccomplish a rapid reduction of the surface temperature and the secondquenching zone can be used to lower the interior temperature of themetal workpiece to the desired level while maintaining the low surfacetemperature obtained in the first quenching zone.

Where straightness of the product is important, the metal workpiece isrestrained during quenching to minimize or preclude distortion duringthe drastic temperature La reduction which occurs on quenching. In theprocessing of steel structural shapes, to which the invention isespecially well suited, the restraint must be considerable and is bestaccomplished with groups of four rolls arranged in pairs, horizontallyand vertically around the steel beam to confine it. Many such groups ofrolls will be used for long beams and some may be located within thesecond quenching zone.

Other aspects and advantages of the invention will be more evident bythe following description taken together with the drawings wherein:

FIGURE 1 is a schematic side elevation partly in section of a preferredembodiment of the quenching apparatus;

FiGURE 2 is a section taken along lines lIIi of FIG- URE 1 showing thegas-curtain portion of the first quenching zone;

FIGURE 3 is a section taken along lines TIL-III of FIGURE 1 showing theliquid coolant portion of the first quenching zone;

FIGURE 4 is a vertical cross section taken along lines IVIV of FIGURE 2;and

FIGURE 5 is a sectional view taken along lines VV of FIGURE 1 throughthe second quenching zone.

As is seen in FIGURE 1, a metal workpiece 8 passes through the quenchingapparatus as it emerges from the heat treating furnace 1h. The metalworkpiece 8 is advantageously restrained during quenching by horizontaland vertical rolls positioned throughout the quenching apparatus. It isnecessary to restrain the metal workpiece during the rapid temperaturereduction to obtain maximum straightness. The first set of rollsillustrated include horizontal rolls 14a and 14b and vertical rolls 16a.The first quenching zone comprises the aforementioned combination ofspaced apart gas and liquid coolant curtains arranged so as to provide asubstantially planar mass of gas and a substantailly planar mass ofliquid coolant across the passageways in each of the plate iembers 2%and 30, respectively. The first plate member 28 is secured to and spacedfrom second plate member 36} by means of bolts 26 and sleeves 26. Theplates are spaced apart in such a manner as to permit the gas to escapewith minimum turbulence. Plate member 30 is in turn secured to a frameor housing 29 by quick disconnect fasteners 28. Quick disconnectcouplings 23a and 23b permit the gas and coolant lines, respectively, toalso be rapidly disconnected. Each of the plate members 20 and 30contains a passageway for the metal workpiece which preferably conformsto the configuration of the workpiece. In the embodiment illustrated,the workpiece is shown as a steel I-beam; however, it is apparent thatother cross sections can be similarly treated and when other shapes areproc cssed, plate members 20 and 30 can be replaced with other plateshaving passageways generally conforming to the shape to be processed. Tofacilitate rapid replacement of the quenching plates, the aforementionedquick disconnect fasteners 28 are employed and both plate members 20 and3%) can be removed as a unit with a similar unit having appropriatelyshaped passageways quickly substituted therefor.

As is best seen in FIGURES l and 2, air is supplied to plate member 20by nozzles 24a, 24b, 24c and 2412' which are distributed around thepassageway and which direct gas against the plate surrounding orcircumscribing the passageway 41 Gas is supplied to the nozzles bymanifolds 22a, 22b, 22c and 22b. Connected to each of the manifolds butshown for simplicity as connected to only one thereof, is a fluid line21 which receives gas from a suitable supply such as a compressor (notshown). A pressure regulator 23 may be advantageously included alongwith valve 25 and flow meter 27 to insure a measured and controlledsupply of gas to each of the manifolds.

The second plate member 3t? supports the first plate member 20 to whichit is fastened and is in turn supported on a frame 29 by quickdisconnect couplings 28.

As best seen in FIGURES l and 3, liquid coolant is supplied against thesurface of plate member 39 by a plurality of nozzles positioned tosurround the passageway d2. Nozzles 34a, 34c and 34b receive liquidcoolant from headers 32a, 32b, 32c and 32b respectively. Each of theheaders is preferably connected to an independent coolant supply but forsimplicity only one such line is shown in the drawings. As can be seen,liquid coolant is supplied through line 31 from a suitable supply orreservoir by a pump 33. A pressure regulator 35, a control valve 37' anda flow meter 39 may be advantageously used to furnish a measured andcontrolled supply of liquid coolant to each of the headers.

The second quenching zone is located adjacent the first quenching zoneand may comprise any suitable means for delivering coolant to theworkpiece in sufiicient quantity to lower the interior temperature ofthe metal workpiece to the desired level while maintaining the surfacetemperature at substantially that obtained in the first quenching zone.In the embodiment shown, the second quenching zone comprises a suitablehousing within which is disposed a plurality of horizontal restrainingrolls 54a, 54b, 56a, 56/], 58a and 58b which coact with a plurality ofvertical restraining rolls 54c, 56c and 58c. The horizontal and verticalrolls are present in pairs on opposite sides of the metal workpiece, asbest shown in FIGURE 5. Within housing 5t} are disposed a plurality ofconventional spray nozzles and coolant supply headers 52a, 52b, 52c,5261, 52c, 52], 52x, 52y and 522. Each of the headers in the secondquenching zone is supplied with liquid coolant in a conventional manner.Since the function of this quenching zone is simply to withdraw heatfrom the interior of the metal workpiece as rapidly as possible, it isonly necessary to supply coolant in suflicient quantity to extract heatfrom the metal workpiece as quickly as possible. A drain 57 may beprovided for convenience, The requirements for the second quenching Zoneare less rigorous than those of the first quenching zone. In the secondzone, it is only necessary to keep the entire surface of the workcontinuously wet with coolant to insure constant heat removal from theinterior of the workpiece.

The manner in which the combined plate members in the first quenchingzone function to provide a fine quenching line around the periphery ofthe metal is best seen in FIGURE 4. The passageways in plate members 20and 30 are preferably beveled as shown to assist in providing a thinline of contact of the gas and liquid coolant onto the metal workpiece.Gas supplied against the surface of plate member 20 surrounding thepassageway 40, which conforms generally to the configuration of themetal workpiece 8, is supplied in sufficient volume and velocity toeffectively retard and prevent back flow of liquid coolant afterimpingement against the metal workpiece 8. This gas flow 44- is showndiagrammatically and extends substantially to plate member 36. Ifsplashing of the coolant was not restricted, the total flow of coolanton the workpiece would be divided so that half would flow forward on theworkpiece and half flow backward toward the furnace. Back flow must, ofcourse, be avoided to prevent injury to furnace operation as well as tominimize premature cooling of the workpiece.

Where .straightness of the product is a significant factor, it is, ashas been described above, advantageous to restrain the metal workpieceduring quenching. A suitable arrangement for this purpose is thecombination of horizontal and vertical rolls described above. Thearrangement of the rolls in this fashion is best shown in FIGURE 5 whichshows one such assembly in the second quench zone. As can be seen,horizontal rolls 54a and 54b coact with vertical rolls 54c and 54a toconfine the metal workpiece 8. FIGURE 5 also shows typical dispositionsof sprays 5212, 52y, 52c and 52y surrounding the workpiece within thesecond quenching zone. The groups of restraining rolls which may also beused to convey as well as support the work should be as closely coupledas possible, consistent with operating and maintenance requirements. Tofacilitate a compact arrangement, the roll groups may be supported byhousings (not shown) common to all rather than by individual housings.The rolls may also be either individually driven or driven from a commondrive, and the roll spacing should be adjustable to accommodate avariety of work. An integrated control system may be provided to insurethat all roll drives are speed matched and either electric motor orfluid power drives may be used.

As an example of the operation of the invention, a 16-inch, wide-flangebeam Weighing 78 lb./ft. moving through the furnace at 3.75 f.p.m. canbe quenched from a temperature of about 1800" F. to about 300 F. with atotal water flow of about 460 g.-p.m. divided so that about half issupplied in each of the two quenching zones. Where, as in the preferredembodiment, a low nozzle pressure, eg 25 psi, is used to encouragelaminar flow, 30 nozzles or outlets of Ar-inch inside diameterdistributed so as to discharge coolant around the passageway can beemployed in the first quenching zone. This can be accomplished with tenoutlets on about 2-inch centers directing coolant toward each flange (20coolant outlets total) and 5 outlet on about 3-inch centers directingcoolant toward each side of the web' To prevent back flow of water, airis supplied to the first plate ahead of the water plate through 30 -inchnozzles each delivering 4 c. f.m. of air at 60 psi. The air nozzles aresimilarly positioned around the passageway. While the requirements areless rigorous, coolant supplied in the second quench should bedistributed over the length of the work within it so that maximum heatremoval is achieved. The nozzles used in this zone will be able toproject sprays onto the entire surface of the work to maintainsubstantially the same surface temperature achieved in the firstquenching zone while cooling the interior to the desired lowtemperature.

It is apparent that various changes and modifications may be madewithout departing from the invention. Spacing between the plates in thefirst quenching zone may be varied to produce different effects asdesired; however, with increased spacing the effectiveness of the gascurtain in preventing back fiow of liquid coolant is lessened. It isalso desirable to minimize turbulence of gas and cooland between theplates, as this also reduces the effectiveness of the gas curtain. Asmight be expected, the quantity of gas required to prevent back flow ofcoolant increases as the coolant flow is increased. However, optimumadjustments can be readily arrived at for specific equipment. It is alsoobvious that relatively simple cross sections such as slabs or plate maybe proceed as well a structural shapes and beams.

I claim:

1. An apparatus for quenching metal adaptable for use in a continuousprocessing system comprising first and second plate members spaced fromeach other and having aligned passageways therein for passage of metaltherethrough, said plate members being disposed substantiallyperpendicular to the line of travel of said metal, means to propel gasagainst the surface of said first plate member surrounding thepassageway therein and means to propel liquid coolant against thesurface of said second plate member surrounding the passageway therein,whereby a substantially planar mass of gas and a substantially planarmass of liquid coolant are provided across the passageways of said firstand second plate members, respectively.

2. An apparatus for quenching metal adaptable for use in a continuousprocessing system comprising first and second quenching zones, saidfirst quenching zone comprising first and second plate members spacedfrom each other and having aligned passageways therein for passage ofmetal therethrough, said plate members being disposed substantiallyperpendicular to the line of travel of said metal, means to propel gasagainst the surface of said first plate member surrounding thepassageway therein and means to propel liquid coolant against thesurface of said second plate member surrounding the passageway therein,whereby a substantially planar mass of gas and a substantially planarmass of liquid coolant are provided across the passageways of said firstand second plate members, respectively; said second quenching zone beingpositioned adjacent to said first quenching zone and adapted to receivemetal therefrom, said second quenching zone comprising means to delivercoolant into contact with said metal to extract heat therefrom.

3. An apparatus for quenching metal adaptable for use in a continuousprocessing system comprising first and second quenching zones and meansto restrain said metal to substantially prevent distortion thereofduring quenching, said first quenching zone comprising first and secondplate members spaced from each other and having aligned passagewaystherein for passage of metal therethrough, said plate members beingdisposed substantially perpendicular to the line of travel of saidmetal, means to propel gas against the surface of said first platemember surrounding the passageway therein and means to propel liquidcoolant against the surface of said second plate member surrounding thepassageway therein, whereby a substantially planar mass of gas and asubstantially planar mass of liquid coolant are provided across thepassageways of said first and second plate members, respectively; saidsecond quenching zone being positioned adjacent to said first quenchingzone and adapted to receive metal therefrom, said second quenching zonecomprising means to deliver coolant into contact with said metal toextract heat therefrom.

4. An apparatus for quenching metal adapt-able for use in a continuousprocessing system comprising first and second quenching zones and meansto restrain said metal to substantially prevent distortion thereofduring quenching, said first quenching zone comprising first and secondplate members spaced from each other and having aligned passagewaystherein for passage of metal therethrough, said plate members beingdisposed substantially perpendicular to the line of travel of saidmetal, means to propel gas against the surface of said first platemember surrounding the passageway therein and means to propel liquidcoolant against the surface of said second plate member surrounding thepassageway therein, whereby a substantially planar mass of gas and asubstantially planar mass of liquid coolant are provided across thepassageways of said first and second plate members, respectively; saidsecond quenching zone being positioned adjacent to said first quenchingzone and adapted to receive metal therefrom, said second quenching zonecomprising means to deliver coolant into contact with said metal toextract heat therefrom; said means to restrain said metal duringquenching being disposed ahead of said first quenching zone and withinsaid second quenching zone.

5. An apparatus according to claim 4 wherein said means to restrain saidmetal during quenching comprises groups of rolls and each group of rollscomprises a pair of horizontally disposed rolls and a pair of verticallydisposed rolls, said horizontally disposed rolls being adapted tocontact the top and bottom of said metal and said vertically disposedrolls being adapted to contact opposite sides of said metal.

6. In a process of heat treating metal wherein said metal is quenchedafter passing through a heat treating furnace, the improvementcomprising passing said metal as it comes out of said furnace through aquenching zone comprising a plane of high velocity gas and a plane ofcoolant, both of which are substantially perpendicular to the line oftravel of said metal, the velocity and volume of said gas beingsuflicient to substantially prevent said coolant from flowing in adirection opposite to the direction of travel of said metal afterimpingement upon said metal.

7. A method of quenching metal as it emerges from a heat treatingfurnace comprising passing said metal through a first quenching zone torapidly lower the surface temperature of said metal and then passingsaid metal through a second quenching zone to lower the internaltemperature of said metal, the temperature of the surface of said metalbeing rapidly reduced in said first quenching zone 'by passing saidmetal through a plane of high velocity gas and a plane of liquidcoolant, both of which are substantially perpendicular to the line oftravel of said metal, the velocity and volume of said gas beingsuflicient to substantially prevent said liquid coolant from flowing ina direction opposite to the direction of travel of said metal afterimpingement upon said metal.

8. A method of quenching metal as it emerges from a heat treatingfurnace comprising passing said metal through :a first quenching zone torapidly lower the surface temperature of said metal and then passingsaid metal through a second quenching zone to lower the internal"temperature of said metal and restraining said metal while passing samethrough said first and second quenching zones to substantially preventdistortion thereof, the temperature of the surface of said metal beingrapidly reduced in said first quenching zone by passing said metalthrough a plane of high velocity gas and a plane of liquid coolant, bothof which are substantially perpendicular to the line of travel of saidmetal, the velocity and volume of said gas being suflicient tosubstantially prevent said liquid coolant from flowing in a directionopposite to the direction of travel of said metal after impingement uponsaid metal.

References Cited UNITED STATES PAT ENTS 3,036,825 5/1962 Eisenrnenger2664 3,148,093 9/1964 Williams et a1. 148-445 X 3,208.7 9/ 1965 Peretick266-4 FOREIGN PATENTS 870,556 6/1961 Great Britain.

CHARLES N. LOVELL, Primary Examiner.

